1. Field of the Invention
The present invention relates generally to storage-area networks comprising diskless servers and computer data storage systems and, more specifically, to configuring a diskless server newly added to a storage-area network.
2. Description of the Related Art
The common computing system paradigm for business enterprises has evolved from stand-alone computers, each operated by an individual user, to client-server systems in which a remote server computer provides the computing power to service client computers operated by users via a network. Client-server systems vary widely in the distribution of computing power, storage and other resources between the client and the server. For example, in some client-server systems, clients are termed “thin clients” because resources are concentrated in the server. In others, clients are powerful workstations having substantial storage and processing resources.
Another shift in the computing paradigm has been toward a model in which data storage is centralized. Individual workstations or other servers throughout an enterprise are networked to a central data storage subsystem that they use to a greater extent than their internal hard disks or even to the exclusion of internal disks. In some systems, the servers are completely diskless, with operating system software, application programs and data all stored in the central data storage subsystem. The network may be referred to as a storage-area network (SAN). The SAN model is particularly attractive for data centers and similar enterprises in which a substantial number of servers needs access to a central repository of data. Storage products for such systems are commercially available from a variety of sources, such as EMC Corporation of Hopkinton, Mass. Systems are contemplated in which all of an enterprise's data storage needs are centralized, with the central data storage subsystem communicating remotely with diskless servers via a network protocol that supports communication over substantial distances, such as optical-media Fibre Channel. One advantage of diskless servers in a data center environment is that, if one fails, it can be quickly and easily replaced because there is no software to reinstall. Rather than having its operating system and other configuration software stored on a local disk, a diskless server dynamically obtains such software from the SAN during the boot process.
Installing new diskless servers in a data center environment, in which the enterprise may have many servers (hosts) running different operating systems, may tax the resources of a system administration department. If a server fails or otherwise needs to be replaced, or an additional server needs to be added, SAN ports and storage volumes must be assigned to the new host, and the operating system and application programs pertaining to the new host must then be installed on the SAN. This process often requires cooperation between the system administration department and a separate department in the enterprise that is charged with assigning ports and volumes and otherwise maintaining the central data storage devices. System administration personnel typically install operating systems and other software by loading from CD-ROMs or similar media or by using the so-called ghost image method by which software can be installed remotely via the network. Before beginning the installation process, such personnel must first identify the operating system that is to be installed and ensure that a copy is on hand. The overall process for adding a new host to a network can thus be time consuming and inefficient.
In contrast to the laborious process noted above for adding a new device to a SAN in a Fibre Channel or similar environment, adding devices to a network in an Internet Protocol (IP) network environment is increasingly easy with the advent of so-called “plug-and-play” concepts. In the Universal Plug and Play (UPnP) model, for example, promulgated by Microsoft Corporation, a newly connected device acts as a Dynamic Host Configuration Protocol (DHCP) client and searches the network for a DHCP server. DHCP is a mechanism for providing device configuration information needed to access the Internet. If a DHCP server is available, the device obtains an IP address from it. The device then advertises its services to control points on the network. Similarly, when a control point is added to the network, the UPnP discovery protocol allows that control point to search for devices of interest on the network.
It would be desirable to be able to add a diskless server to a SAN with essentially the same ease as adding a plug-and-play device to an IP-based network. The present invention addresses this problem and others in the manner described below.